1. Field of the Invention
The present invention relates to the technical field of light condensing lenses and three-dimensional distance measuring apparatuses. More particularly, the present invention relates to the technical field of light condensing lenses for condensing laser light on a light receiving element including a plurality of lenses disposed side by side in a splitting direction of a view angle to secure a sufficient amount of light received by the light receiving element and to reduce the light receiving area of the light receiving element.
2. Description of the Related Art
There are some distance measuring apparatuses that measure the distance to an object to be measured using laser light as measurement light.
Examples of such distance measuring apparatuses include an apparatus that modulates laser light and irradiates an object to be measured with the modulated laser light to measure a distance by detecting the phase difference between the light emitted from a laser light source toward the object to be measured and the light incident on a light receiving element after being reflected by the object to be measured.
Other examples include a distance measuring apparatus that emits a laser pulse to an object to be measured to measure a distance by measuring the round-trip period of the laser pulse from the emission from a laser light source to the incidence on a light receiving element after the laser pulse is reflected by the object to be measured.
The distance measuring apparatuses described above may be, for example, incorporated in an industrial robot to measure the distance from the robot to an object to be measured provided around the robot, incorporated in a vehicle to measure the distance between vehicles, and so forth. The distance measuring apparatuses may also be incorporated in a gaming device to measure the distance from a predetermined position to a user as an object to be measured.
In some distance measuring apparatuses, a light projecting mirror is turned in a predetermined direction to linearly scan an object to be measured with laser light reflected by the light projecting mirror in order to measure a two-dimensional distance (see Japanese Patent No. 3908226, Japanese Patent No. 3875665, and Japanese Unexamined Patent Application Publication No. 2009-162659, for example).
In other distance measuring apparatuses, the entire apparatus is turned about a turning axis that is different from the turning axis of a light projecting mirror, or a group of prisms is turned to expand a scanning region for an object to be measured in order to measure a three-dimensional distance (see Japanese Patent No. 4059911 and Japanese Unexamined Patent Application Publication No. 07-98379, for example).
In still other distance measuring apparatuses, scanning is repeatedly performed with laser light using a galvano mirror or a MEMS (Micro Electro Mechanical Systems) mirror as a light projecting mirror to measure a two-dimensional or three-dimensional distance.